tracing cleanups for v6.17:

- Remove unneeded goto out statements
 
   Over time, the logic was restructured but left a "goto out" where the
   out label simply did a "return ret;". Instead of jumping to this out
   label, simply return immediately and remove the out label.
 
 - Add guard(ring_buffer_nest)
 
   Some calls to the tracing ring buffer can happen when the ring buffer is
   already being written to at the same context (for example, a
   trace_printk() in between a ring_buffer_lock_reserve() and a
   ring_buffer_unlock_commit()).
 
   In order to not trigger the recursion detection, these functions use
   ring_buffer_nest_start() and ring_buffer_nest_end(). Create a guard() for
   these functions so that their use cases can be simplified and not need to
   use goto for the release.
 
 - Clean up the tracing code with guard() and __free() logic
 
   There were several locations that were prime candidates for using guard()
   and __free() helpers. Switch them over to use them.
 
 - Fix output of function argument traces for unsigned int values
 
   The function tracer with "func-args" option set will record up to 6 argument
   registers and then use BTF to format them for human consumption when the
   trace file is read. There's several arguments that are "unsigned long" and
   even "unsigned int" that are either and address or a mask. It is easier to
   understand if they were printed using hexadecimal instead of decimal.
   The old method just printed all non-pointer values as signed integers,
   which made it even worse for unsigned integers.
 
   For instance, instead of:
 
     __local_bh_disable_ip(ip=-2127311112, cnt=256) <-handle_softirqs
 
   Show:
 
    __local_bh_disable_ip(ip=0xffffffff8133cef8, cnt=0x100) <-handle_softirqs
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Merge tag 'trace-v6.17-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull more tracing updates from Steven Rostedt:

 - Remove unneeded goto out statements

   Over time, the logic was restructured but left a "goto out" where the
   out label simply did a "return ret;". Instead of jumping to this out
   label, simply return immediately and remove the out label.

 - Add guard(ring_buffer_nest)

   Some calls to the tracing ring buffer can happen when the ring buffer
   is already being written to at the same context (for example, a
   trace_printk() in between a ring_buffer_lock_reserve() and a
   ring_buffer_unlock_commit()).

   In order to not trigger the recursion detection, these functions use
   ring_buffer_nest_start() and ring_buffer_nest_end(). Create a guard()
   for these functions so that their use cases can be simplified and not
   need to use goto for the release.

 - Clean up the tracing code with guard() and __free() logic

   There were several locations that were prime candidates for using
   guard() and __free() helpers. Switch them over to use them.

 - Fix output of function argument traces for unsigned int values

   The function tracer with "func-args" option set will record up to 6
   argument registers and then use BTF to format them for human
   consumption when the trace file is read. There are several arguments
   that are "unsigned long" and even "unsigned int" that are either and
   address or a mask. It is easier to understand if they were printed
   using hexadecimal instead of decimal. The old method just printed all
   non-pointer values as signed integers, which made it even worse for
   unsigned integers.

   For instance, instead of:

     __local_bh_disable_ip(ip=-2127311112, cnt=256) <-handle_softirqs

   show:

     __local_bh_disable_ip(ip=0xffffffff8133cef8, cnt=0x100) <-handle_softirqs"

* tag 'trace-v6.17-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing: Have unsigned int function args displayed as hexadecimal
  ring-buffer: Convert ring_buffer_write() to use guard(preempt_notrace)
  tracing: Use __free(kfree) in trace.c to remove gotos
  tracing: Add guard() around locks and mutexes in trace.c
  tracing: Add guard(ring_buffer_nest)
  tracing: Remove unneeded goto out logic

include/linux/ring_buffer.h

@@ -144,6 +144,9 @@ int ring_buffer_write(struct trace_buffer *buffer,
 void ring_buffer_nest_start(struct trace_buffer *buffer);
 void ring_buffer_nest_end(struct trace_buffer *buffer);
 
+DEFINE_GUARD(ring_buffer_nest, struct trace_buffer *,
+	     ring_buffer_nest_start(_T), ring_buffer_nest_end(_T))
+
 struct ring_buffer_event *
 ring_buffer_peek(struct trace_buffer *buffer, int cpu, u64 *ts,
 		 unsigned long *lost_events);

kernel/trace/ring_buffer.c

@@ -4812,26 +4812,26 @@ int ring_buffer_write(struct trace_buffer *buffer,
 	int ret = -EBUSY;
 	int cpu;
 
-	preempt_disable_notrace();
+	guard(preempt_notrace)();
 
 	if (atomic_read(&buffer->record_disabled))
-		goto out;
+		return -EBUSY;
 
 	cpu = raw_smp_processor_id();
 
 	if (!cpumask_test_cpu(cpu, buffer->cpumask))
-		goto out;
+		return -EBUSY;
 
 	cpu_buffer = buffer->buffers[cpu];
 
 	if (atomic_read(&cpu_buffer->record_disabled))
-		goto out;
+		return -EBUSY;
 
 	if (length > buffer->max_data_size)
-		goto out;
+		return -EBUSY;
 
 	if (unlikely(trace_recursive_lock(cpu_buffer)))
-		goto out;
+		return -EBUSY;
 
 	event = rb_reserve_next_event(buffer, cpu_buffer, length);
 	if (!event)
@@ -4849,10 +4849,6 @@ int ring_buffer_write(struct trace_buffer *buffer,
 
  out_unlock:
 	trace_recursive_unlock(cpu_buffer);
-
- out:
-	preempt_enable_notrace();
-
 	return ret;
 }
 EXPORT_SYMBOL_GPL(ring_buffer_write);

kernel/trace/trace.c

@@ -432,15 +432,13 @@ static void ftrace_exports(struct ring_buffer_event *event, int flag)
 {
 	struct trace_export *export;
 
-	preempt_disable_notrace();
+	guard(preempt_notrace)();
 
 	export = rcu_dereference_raw_check(ftrace_exports_list);
 	while (export) {
 		trace_process_export(export, event, flag);
 		export = rcu_dereference_raw_check(export->next);
 	}
-
-	preempt_enable_notrace();
 }
 
 static inline void
@@ -497,27 +495,18 @@ int register_ftrace_export(struct trace_export *export)
 	if (WARN_ON_ONCE(!export->write))
 		return -1;
 
-	mutex_lock(&ftrace_export_lock);
+	guard(mutex)(&ftrace_export_lock);
 
 	add_ftrace_export(&ftrace_exports_list, export);
 
-	mutex_unlock(&ftrace_export_lock);
-
 	return 0;
 }
 EXPORT_SYMBOL_GPL(register_ftrace_export);
 
 int unregister_ftrace_export(struct trace_export *export)
 {
-	int ret;
-
-	mutex_lock(&ftrace_export_lock);
-
-	ret = rm_ftrace_export(&ftrace_exports_list, export);
-
-	mutex_unlock(&ftrace_export_lock);
-
-	return ret;
+	guard(mutex)(&ftrace_export_lock);
+	return rm_ftrace_export(&ftrace_exports_list, export);
 }
 EXPORT_SYMBOL_GPL(unregister_ftrace_export);
 
@@ -640,9 +629,8 @@ void trace_array_put(struct trace_array *this_tr)
 	if (!this_tr)
 		return;
 
-	mutex_lock(&trace_types_lock);
+	guard(mutex)(&trace_types_lock);
 	__trace_array_put(this_tr);
-	mutex_unlock(&trace_types_lock);
 }
 EXPORT_SYMBOL_GPL(trace_array_put);
 
@@ -1160,13 +1148,11 @@ int __trace_array_puts(struct trace_array *tr, unsigned long ip,
 
 	trace_ctx = tracing_gen_ctx();
 	buffer = tr->array_buffer.buffer;
-	ring_buffer_nest_start(buffer);
+	guard(ring_buffer_nest)(buffer);
 	event = __trace_buffer_lock_reserve(buffer, TRACE_PRINT, alloc,
 					    trace_ctx);
-	if (!event) {
-		size = 0;
-		goto out;
-	}
+	if (!event)
+		return 0;
 
 	entry = ring_buffer_event_data(event);
 	entry->ip = ip;
@@ -1182,8 +1168,6 @@ int __trace_array_puts(struct trace_array *tr, unsigned long ip,
 
 	__buffer_unlock_commit(buffer, event);
 	ftrace_trace_stack(tr, buffer, trace_ctx, 4, NULL);
- out:
-	ring_buffer_nest_end(buffer);
 	return size;
 }
 EXPORT_SYMBOL_GPL(__trace_array_puts);
@@ -1213,7 +1197,6 @@ int __trace_bputs(unsigned long ip, const char *str)
 	struct bputs_entry *entry;
 	unsigned int trace_ctx;
 	int size = sizeof(struct bputs_entry);
-	int ret = 0;
 
 	if (!printk_binsafe(tr))
 		return __trace_puts(ip, str, strlen(str));
@@ -1227,11 +1210,11 @@ int __trace_bputs(unsigned long ip, const char *str)
 	trace_ctx = tracing_gen_ctx();
 	buffer = tr->array_buffer.buffer;
 
-	ring_buffer_nest_start(buffer);
+	guard(ring_buffer_nest)(buffer);
 	event = __trace_buffer_lock_reserve(buffer, TRACE_BPUTS, size,
 					    trace_ctx);
 	if (!event)
-		goto out;
+		return 0;
 
 	entry = ring_buffer_event_data(event);
 	entry->ip			= ip;
@@ -1240,10 +1223,7 @@ int __trace_bputs(unsigned long ip, const char *str)
 	__buffer_unlock_commit(buffer, event);
 	ftrace_trace_stack(tr, buffer, trace_ctx, 4, NULL);
 
-	ret = 1;
- out:
-	ring_buffer_nest_end(buffer);
-	return ret;
+	return 1;
 }
 EXPORT_SYMBOL_GPL(__trace_bputs);
 
@@ -1432,13 +1412,8 @@ static int tracing_arm_snapshot_locked(struct trace_array *tr)
 
 int tracing_arm_snapshot(struct trace_array *tr)
 {
-	int ret;
-
-	mutex_lock(&trace_types_lock);
-	ret = tracing_arm_snapshot_locked(tr);
-	mutex_unlock(&trace_types_lock);
-
-	return ret;
+	guard(mutex)(&trace_types_lock);
+	return tracing_arm_snapshot_locked(tr);
 }
 
 void tracing_disarm_snapshot(struct trace_array *tr)
@@ -1841,7 +1816,7 @@ int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
 
 	ret = get_user(ch, ubuf++);
 	if (ret)
-		goto out;
+		return ret;
 
 	read++;
 	cnt--;
@@ -1855,7 +1830,7 @@ int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
 		while (cnt && isspace(ch)) {
 			ret = get_user(ch, ubuf++);
 			if (ret)
-				goto out;
+				return ret;
 			read++;
 			cnt--;
 		}
@@ -1865,8 +1840,7 @@ int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
 		/* only spaces were written */
 		if (isspace(ch) || !ch) {
 			*ppos += read;
-			ret = read;
-			goto out;
+			return read;
 		}
 	}
 
@@ -1874,13 +1848,12 @@ int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
 	while (cnt && !isspace(ch) && ch) {
 		if (parser->idx < parser->size - 1)
 			parser->buffer[parser->idx++] = ch;
-		else {
-			ret = -EINVAL;
-			goto out;
-		}
+		else
+			return -EINVAL;
+
 		ret = get_user(ch, ubuf++);
 		if (ret)
-			goto out;
+			return ret;
 		read++;
 		cnt--;
 	}
@@ -1895,15 +1868,11 @@ int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
 		/* Make sure the parsed string always terminates with '\0'. */
 		parser->buffer[parser->idx] = 0;
 	} else {
-		ret = -EINVAL;
-		goto out;
+		return -EINVAL;
 	}
 
 	*ppos += read;
-	ret = read;
-
-out:
-	return ret;
+	return read;
 }
 
 /* TODO add a seq_buf_to_buffer() */
@@ -2405,10 +2374,10 @@ int __init register_tracer(struct tracer *type)
 	mutex_unlock(&trace_types_lock);
 
 	if (ret || !default_bootup_tracer)
-		goto out_unlock;
+		return ret;
 
 	if (strncmp(default_bootup_tracer, type->name, MAX_TRACER_SIZE))
-		goto out_unlock;
+		return 0;
 
 	printk(KERN_INFO "Starting tracer '%s'\n", type->name);
 	/* Do we want this tracer to start on bootup? */
@@ -2420,8 +2389,7 @@ int __init register_tracer(struct tracer *type)
 	/* disable other selftests, since this will break it. */
 	disable_tracing_selftest("running a tracer");
 
- out_unlock:
-	return ret;
+	return 0;
 }
 
 static void tracing_reset_cpu(struct array_buffer *buf, int cpu)
@@ -2498,9 +2466,8 @@ void tracing_reset_all_online_cpus_unlocked(void)
 
 void tracing_reset_all_online_cpus(void)
 {
-	mutex_lock(&trace_types_lock);
+	guard(mutex)(&trace_types_lock);
 	tracing_reset_all_online_cpus_unlocked();
-	mutex_unlock(&trace_types_lock);
 }
 
 int is_tracing_stopped(void)
@@ -2511,18 +2478,17 @@ int is_tracing_stopped(void)
 static void tracing_start_tr(struct trace_array *tr)
 {
 	struct trace_buffer *buffer;
-	unsigned long flags;
 
 	if (tracing_disabled)
 		return;
 
-	raw_spin_lock_irqsave(&tr->start_lock, flags);
+	guard(raw_spinlock_irqsave)(&tr->start_lock);
 	if (--tr->stop_count) {
 		if (WARN_ON_ONCE(tr->stop_count < 0)) {
 			/* Someone screwed up their debugging */
 			tr->stop_count = 0;
 		}
-		goto out;
+		return;
 	}
 
 	/* Prevent the buffers from switching */
@@ -2539,9 +2505,6 @@ static void tracing_start_tr(struct trace_array *tr)
 #endif
 
 	arch_spin_unlock(&tr->max_lock);
-
- out:
-	raw_spin_unlock_irqrestore(&tr->start_lock, flags);
 }
 
 /**
@@ -2559,11 +2522,10 @@ void tracing_start(void)
 static void tracing_stop_tr(struct trace_array *tr)
 {
 	struct trace_buffer *buffer;
-	unsigned long flags;
 
-	raw_spin_lock_irqsave(&tr->start_lock, flags);
+	guard(raw_spinlock_irqsave)(&tr->start_lock);
 	if (tr->stop_count++)
-		goto out;
+		return;
 
 	/* Prevent the buffers from switching */
 	arch_spin_lock(&tr->max_lock);
@@ -2579,9 +2541,6 @@ static void tracing_stop_tr(struct trace_array *tr)
 #endif
 
 	arch_spin_unlock(&tr->max_lock);
-
- out:
-	raw_spin_unlock_irqrestore(&tr->start_lock, flags);
 }
 
 /**
@@ -2694,12 +2653,12 @@ void trace_buffered_event_enable(void)
 
 		per_cpu(trace_buffered_event, cpu) = event;
 
-		preempt_disable();
-		if (cpu == smp_processor_id() &&
-		    __this_cpu_read(trace_buffered_event) !=
-		    per_cpu(trace_buffered_event, cpu))
-			WARN_ON_ONCE(1);
-		preempt_enable();
+		scoped_guard(preempt,) {
+			if (cpu == smp_processor_id() &&
+			    __this_cpu_read(trace_buffered_event) !=
+			    per_cpu(trace_buffered_event, cpu))
+				WARN_ON_ONCE(1);
+		}
 	}
 }
 
@@ -3044,7 +3003,7 @@ static void __ftrace_trace_stack(struct trace_array *tr,
 		skip++;
 #endif
 
-	preempt_disable_notrace();
+	guard(preempt_notrace)();
 
 	stackidx = __this_cpu_inc_return(ftrace_stack_reserve) - 1;
 
@@ -3102,8 +3061,6 @@ static void __ftrace_trace_stack(struct trace_array *tr,
 	/* Again, don't let gcc optimize things here */
 	barrier();
 	__this_cpu_dec(ftrace_stack_reserve);
-	preempt_enable_notrace();
-
 }
 
 static inline void ftrace_trace_stack(struct trace_array *tr,
@@ -3186,9 +3143,9 @@ ftrace_trace_userstack(struct trace_array *tr,
 	 * prevent recursion, since the user stack tracing may
 	 * trigger other kernel events.
 	 */
-	preempt_disable();
+	guard(preempt)();
 	if (__this_cpu_read(user_stack_count))
-		goto out;
+		return;
 
 	__this_cpu_inc(user_stack_count);
 
@@ -3206,8 +3163,6 @@ ftrace_trace_userstack(struct trace_array *tr,
 
  out_drop_count:
 	__this_cpu_dec(user_stack_count);
- out:
-	preempt_enable();
 }
 #else /* CONFIG_USER_STACKTRACE_SUPPORT */
 static void ftrace_trace_userstack(struct trace_array *tr,
@@ -3389,7 +3344,7 @@ int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
 	pause_graph_tracing();
 
 	trace_ctx = tracing_gen_ctx();
-	preempt_disable_notrace();
+	guard(preempt_notrace)();
 
 	tbuffer = get_trace_buf();
 	if (!tbuffer) {
@@ -3404,26 +3359,23 @@ int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
 
 	size = sizeof(*entry) + sizeof(u32) * len;
 	buffer = tr->array_buffer.buffer;
-	ring_buffer_nest_start(buffer);
-	event = __trace_buffer_lock_reserve(buffer, TRACE_BPRINT, size,
-					    trace_ctx);
-	if (!event)
-		goto out;
-	entry = ring_buffer_event_data(event);
-	entry->ip			= ip;
-	entry->fmt			= fmt;
+	scoped_guard(ring_buffer_nest, buffer) {
+		event = __trace_buffer_lock_reserve(buffer, TRACE_BPRINT, size,
+						    trace_ctx);
+		if (!event)
+			goto out_put;
+		entry = ring_buffer_event_data(event);
+		entry->ip			= ip;
+		entry->fmt			= fmt;
 
-	memcpy(entry->buf, tbuffer, sizeof(u32) * len);
-	__buffer_unlock_commit(buffer, event);
-	ftrace_trace_stack(tr, buffer, trace_ctx, 6, NULL);
-
-out:
-	ring_buffer_nest_end(buffer);
+		memcpy(entry->buf, tbuffer, sizeof(u32) * len);
+		__buffer_unlock_commit(buffer, event);
+		ftrace_trace_stack(tr, buffer, trace_ctx, 6, NULL);
+	}
 out_put:
 	put_trace_buf();
 
 out_nobuffer:
-	preempt_enable_notrace();
 	unpause_graph_tracing();
 
 	return len;
@@ -3447,7 +3399,7 @@ int __trace_array_vprintk(struct trace_buffer *buffer,
 	pause_graph_tracing();
 
 	trace_ctx = tracing_gen_ctx();
-	preempt_disable_notrace();
+	guard(preempt_notrace)();
 
 
 	tbuffer = get_trace_buf();
@@ -3459,24 +3411,22 @@ int __trace_array_vprintk(struct trace_buffer *buffer,
 	len = vscnprintf(tbuffer, TRACE_BUF_SIZE, fmt, args);
 
 	size = sizeof(*entry) + len + 1;
-	ring_buffer_nest_start(buffer);
-	event = __trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
-					    trace_ctx);
-	if (!event)
-		goto out;
-	entry = ring_buffer_event_data(event);
-	entry->ip = ip;
-
-	memcpy(&entry->buf, tbuffer, len + 1);
-	__buffer_unlock_commit(buffer, event);
-	ftrace_trace_stack(printk_trace, buffer, trace_ctx, 6, NULL);
+	scoped_guard(ring_buffer_nest, buffer) {
+		event = __trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
+						    trace_ctx);
+		if (!event)
+			goto out;
+		entry = ring_buffer_event_data(event);
+		entry->ip = ip;
 
+		memcpy(&entry->buf, tbuffer, len + 1);
+		__buffer_unlock_commit(buffer, event);
+		ftrace_trace_stack(printk_trace, buffer, trace_ctx, 6, NULL);
+	}
 out:
-	ring_buffer_nest_end(buffer);
 	put_trace_buf();
 
 out_nobuffer:
-	preempt_enable_notrace();
 	unpause_graph_tracing();
 
 	return len;
@@ -4800,20 +4750,16 @@ int tracing_open_file_tr(struct inode *inode, struct file *filp)
 	if (ret)
 		return ret;
 
-	mutex_lock(&event_mutex);
+	guard(mutex)(&event_mutex);
 
 	/* Fail if the file is marked for removal */
 	if (file->flags & EVENT_FILE_FL_FREED) {
 		trace_array_put(file->tr);
-		ret = -ENODEV;
+		return -ENODEV;
 	} else {
 		event_file_get(file);
 	}
 
-	mutex_unlock(&event_mutex);
-	if (ret)
-		return ret;
-
 	filp->private_data = inode->i_private;
 
 	return 0;
@@ -5090,7 +5036,7 @@ tracing_cpumask_read(struct file *filp, char __user *ubuf,
 		     size_t count, loff_t *ppos)
 {
 	struct trace_array *tr = file_inode(filp)->i_private;
-	char *mask_str;
+	char *mask_str __free(kfree) = NULL;
 	int len;
 
 	len = snprintf(NULL, 0, "%*pb\n",
@@ -5101,16 +5047,10 @@ tracing_cpumask_read(struct file *filp, char __user *ubuf,
 
 	len = snprintf(mask_str, len, "%*pb\n",
 		       cpumask_pr_args(tr->tracing_cpumask));
-	if (len >= count) {
-		count = -EINVAL;
-		goto out_err;
-	}
-	count = simple_read_from_buffer(ubuf, count, ppos, mask_str, len);
+	if (len >= count)
+		return -EINVAL;
 
-out_err:
-	kfree(mask_str);
-
-	return count;
+	return simple_read_from_buffer(ubuf, count, ppos, mask_str, len);
 }
 
 int tracing_set_cpumask(struct trace_array *tr,
@@ -5957,9 +5897,9 @@ tracing_set_trace_read(struct file *filp, char __user *ubuf,
 	char buf[MAX_TRACER_SIZE+2];
 	int r;
 
-	mutex_lock(&trace_types_lock);
-	r = sprintf(buf, "%s\n", tr->current_trace->name);
-	mutex_unlock(&trace_types_lock);
+	scoped_guard(mutex, &trace_types_lock) {
+		r = sprintf(buf, "%s\n", tr->current_trace->name);
+	}
 
 	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
 }
@@ -6261,15 +6201,13 @@ int tracing_update_buffers(struct trace_array *tr)
 {
 	int ret = 0;
 
-	mutex_lock(&trace_types_lock);
+	guard(mutex)(&trace_types_lock);
 
 	update_last_data(tr);
 
 	if (!tr->ring_buffer_expanded)
 		ret = __tracing_resize_ring_buffer(tr, trace_buf_size,
 						RING_BUFFER_ALL_CPUS);
-	mutex_unlock(&trace_types_lock);
-
 	return ret;
 }
 
@@ -6566,7 +6504,7 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
 	if (ret)
 		return ret;
 
-	mutex_lock(&trace_types_lock);
+	guard(mutex)(&trace_types_lock);
 	cpu = tracing_get_cpu(inode);
 	ret = open_pipe_on_cpu(tr, cpu);
 	if (ret)
@@ -6610,7 +6548,6 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
 
 	tr->trace_ref++;
 
-	mutex_unlock(&trace_types_lock);
 	return ret;
 
 fail:
@@ -6619,7 +6556,6 @@ fail_alloc_iter:
 	close_pipe_on_cpu(tr, cpu);
 fail_pipe_on_cpu:
 	__trace_array_put(tr);
-	mutex_unlock(&trace_types_lock);
 	return ret;
 }
 
@@ -6628,14 +6564,13 @@ static int tracing_release_pipe(struct inode *inode, struct file *file)
 	struct trace_iterator *iter = file->private_data;
 	struct trace_array *tr = inode->i_private;
 
-	mutex_lock(&trace_types_lock);
+	scoped_guard(mutex, &trace_types_lock) {
+		tr->trace_ref--;
 
-	tr->trace_ref--;
-
-	if (iter->trace->pipe_close)
-		iter->trace->pipe_close(iter);
-	close_pipe_on_cpu(tr, iter->cpu_file);
-	mutex_unlock(&trace_types_lock);
+		if (iter->trace->pipe_close)
+			iter->trace->pipe_close(iter);
+		close_pipe_on_cpu(tr, iter->cpu_file);
+	}
 
 	free_trace_iter_content(iter);
 	kfree(iter);
@@ -7438,7 +7373,7 @@ int tracing_set_clock(struct trace_array *tr, const char *clockstr)
 	if (i == ARRAY_SIZE(trace_clocks))
 		return -EINVAL;
 
-	mutex_lock(&trace_types_lock);
+	guard(mutex)(&trace_types_lock);
 
 	tr->clock_id = i;
 
@@ -7462,8 +7397,6 @@ int tracing_set_clock(struct trace_array *tr, const char *clockstr)
 		tscratch->clock_id = i;
 	}
 
-	mutex_unlock(&trace_types_lock);
-
 	return 0;
 }
 
@@ -7515,15 +7448,13 @@ static int tracing_time_stamp_mode_show(struct seq_file *m, void *v)
 {
 	struct trace_array *tr = m->private;
 
-	mutex_lock(&trace_types_lock);
+	guard(mutex)(&trace_types_lock);
 
 	if (ring_buffer_time_stamp_abs(tr->array_buffer.buffer))
 		seq_puts(m, "delta [absolute]\n");
 	else
 		seq_puts(m, "[delta] absolute\n");
 
-	mutex_unlock(&trace_types_lock);
-
 	return 0;
 }
 
@@ -8111,14 +8042,14 @@ static void clear_tracing_err_log(struct trace_array *tr)
 {
 	struct tracing_log_err *err, *next;
 
-	mutex_lock(&tracing_err_log_lock);
+	guard(mutex)(&tracing_err_log_lock);
+
 	list_for_each_entry_safe(err, next, &tr->err_log, list) {
 		list_del(&err->list);
 		free_tracing_log_err(err);
 	}
 
 	tr->n_err_log_entries = 0;
-	mutex_unlock(&tracing_err_log_lock);
 }
 
 static void *tracing_err_log_seq_start(struct seq_file *m, loff_t *pos)
@@ -8389,7 +8320,7 @@ static int tracing_buffers_release(struct inode *inode, struct file *file)
 	struct ftrace_buffer_info *info = file->private_data;
 	struct trace_iterator *iter = &info->iter;
 
-	mutex_lock(&trace_types_lock);
+	guard(mutex)(&trace_types_lock);
 
 	iter->tr->trace_ref--;
 
@@ -8400,8 +8331,6 @@ static int tracing_buffers_release(struct inode *inode, struct file *file)
 					   info->spare_cpu, info->spare);
 	kvfree(info);
 
-	mutex_unlock(&trace_types_lock);
-
 	return 0;
 }
 
@@ -8609,14 +8538,13 @@ static long tracing_buffers_ioctl(struct file *file, unsigned int cmd, unsigned
 	 * An ioctl call with cmd 0 to the ring buffer file will wake up all
 	 * waiters
 	 */
-	mutex_lock(&trace_types_lock);
+	guard(mutex)(&trace_types_lock);
 
 	/* Make sure the waiters see the new wait_index */
 	(void)atomic_fetch_inc_release(&iter->wait_index);
 
 	ring_buffer_wake_waiters(iter->array_buffer->buffer, iter->cpu_file);
 
-	mutex_unlock(&trace_types_lock);
 	return 0;
 }
 
@@ -8957,12 +8885,12 @@ ftrace_trace_snapshot_callback(struct trace_array *tr, struct ftrace_hash *hash,
  out_reg:
 	ret = tracing_arm_snapshot(tr);
 	if (ret < 0)
-		goto out;
+		return ret;
 
 	ret = register_ftrace_function_probe(glob, tr, ops, count);
 	if (ret < 0)
 		tracing_disarm_snapshot(tr);
- out:
+
 	return ret < 0 ? ret : 0;
 }
 
@@ -9106,10 +9034,9 @@ trace_options_write(struct file *filp, const char __user *ubuf, size_t cnt,
 		return -EINVAL;
 
 	if (!!(topt->flags->val & topt->opt->bit) != val) {
-		mutex_lock(&trace_types_lock);
+		guard(mutex)(&trace_types_lock);
 		ret = __set_tracer_option(topt->tr, topt->flags,
 					  topt->opt, !val);
-		mutex_unlock(&trace_types_lock);
 		if (ret)
 			return ret;
 	}
@@ -9418,7 +9345,7 @@ rb_simple_write(struct file *filp, const char __user *ubuf,
 		return ret;
 
 	if (buffer) {
-		mutex_lock(&trace_types_lock);
+		guard(mutex)(&trace_types_lock);
 		if (!!val == tracer_tracing_is_on(tr)) {
 			val = 0; /* do nothing */
 		} else if (val) {
@@ -9432,7 +9359,6 @@ rb_simple_write(struct file *filp, const char __user *ubuf,
 			/* Wake up any waiters */
 			ring_buffer_wake_waiters(buffer, RING_BUFFER_ALL_CPUS);
 		}
-		mutex_unlock(&trace_types_lock);
 	}
 
 	(*ppos)++;
@@ -9816,10 +9742,9 @@ static void __update_tracer_options(struct trace_array *tr)
 
 static void update_tracer_options(struct trace_array *tr)
 {
-	mutex_lock(&trace_types_lock);
+	guard(mutex)(&trace_types_lock);
 	tracer_options_updated = true;
 	__update_tracer_options(tr);
-	mutex_unlock(&trace_types_lock);
 }
 
 /* Must have trace_types_lock held */
@@ -9841,11 +9766,10 @@ struct trace_array *trace_array_find_get(const char *instance)
 {
 	struct trace_array *tr;
 
-	mutex_lock(&trace_types_lock);
+	guard(mutex)(&trace_types_lock);
 	tr = trace_array_find(instance);
 	if (tr)
 		tr->ref++;
-	mutex_unlock(&trace_types_lock);
 
 	return tr;
 }
@@ -10803,7 +10727,8 @@ ssize_t trace_parse_run_command(struct file *file, const char __user *buffer,
 				size_t count, loff_t *ppos,
 				int (*createfn)(const char *))
 {
-	char *kbuf, *buf, *tmp;
+	char *kbuf __free(kfree) = NULL;
+	char *buf, *tmp;
 	int ret = 0;
 	size_t done = 0;
 	size_t size;
@@ -10818,10 +10743,9 @@ ssize_t trace_parse_run_command(struct file *file, const char __user *buffer,
 		if (size >= WRITE_BUFSIZE)
 			size = WRITE_BUFSIZE - 1;
 
-		if (copy_from_user(kbuf, buffer + done, size)) {
-			ret = -EFAULT;
-			goto out;
-		}
+		if (copy_from_user(kbuf, buffer + done, size))
+			return -EFAULT;
+
 		kbuf[size] = '\0';
 		buf = kbuf;
 		do {
@@ -10837,8 +10761,7 @@ ssize_t trace_parse_run_command(struct file *file, const char __user *buffer,
 					/* This can accept WRITE_BUFSIZE - 2 ('\n' + '\0') */
 					pr_warn("Line length is too long: Should be less than %d\n",
 						WRITE_BUFSIZE - 2);
-					ret = -EINVAL;
-					goto out;
+					return -EINVAL;
 				}
 			}
 			done += size;
@@ -10851,17 +10774,12 @@ ssize_t trace_parse_run_command(struct file *file, const char __user *buffer,
 
 			ret = createfn(buf);
 			if (ret)
-				goto out;
+				return ret;
 			buf += size;
 
 		} while (done < count);
 	}
-	ret = done;
-
-out:
-	kfree(kbuf);
-
-	return ret;
+	return done;
 }
 
 #ifdef CONFIG_TRACER_MAX_TRACE
@@ -11064,7 +10982,7 @@ __init static int tracer_alloc_buffers(void)
 	BUILD_BUG_ON(TRACE_ITER_LAST_BIT > TRACE_FLAGS_MAX_SIZE);
 
 	if (!alloc_cpumask_var(&tracing_buffer_mask, GFP_KERNEL))
-		goto out;
+		return -ENOMEM;
 
 	if (!alloc_cpumask_var(&global_trace.tracing_cpumask, GFP_KERNEL))
 		goto out_free_buffer_mask;
@@ -11182,7 +11100,6 @@ out_free_cpumask:
 	free_cpumask_var(global_trace.tracing_cpumask);
 out_free_buffer_mask:
 	free_cpumask_var(tracing_buffer_mask);
-out:
 	return ret;
 }
 

kernel/trace/trace_events_synth.c

@@ -536,12 +536,12 @@ static notrace void trace_event_raw_event_synth(void *__data,
 	 * is being performed within another event.
 	 */
 	buffer = trace_file->tr->array_buffer.buffer;
-	ring_buffer_nest_start(buffer);
+	guard(ring_buffer_nest)(buffer);
 
 	entry = trace_event_buffer_reserve(&fbuffer, trace_file,
 					   sizeof(*entry) + fields_size);
 	if (!entry)
-		goto out;
+		return;
 
 	for (i = 0, n_u64 = 0; i < event->n_fields; i++) {
 		val_idx = var_ref_idx[i];
@@ -584,8 +584,6 @@ static notrace void trace_event_raw_event_synth(void *__data,
 	}
 
 	trace_event_buffer_commit(&fbuffer);
-out:
-	ring_buffer_nest_end(buffer);
 }
 
 static void free_synth_event_print_fmt(struct trace_event_call *call)

kernel/trace/trace_output.c

@@ -701,6 +701,7 @@ void print_function_args(struct trace_seq *s, unsigned long *args,
 	struct btf *btf;
 	s32 tid, nr = 0;
 	int a, p, x;
+	u16 encode;
 
 	trace_seq_printf(s, "(");
 
@@ -744,7 +745,12 @@ void print_function_args(struct trace_seq *s, unsigned long *args,
 			trace_seq_printf(s, "0x%lx", arg);
 			break;
 		case BTF_KIND_INT:
-			trace_seq_printf(s, "%ld", arg);
+			encode = btf_int_encoding(t);
+			/* Print unsigned ints as hex */
+			if (encode & BTF_INT_SIGNED)
+				trace_seq_printf(s, "%ld", arg);
+			else
+				trace_seq_printf(s, "0x%lx", arg);
 			break;
 		case BTF_KIND_ENUM:
 			trace_seq_printf(s, "%ld", arg);